Vaccination is an effective way to provide prophylactic protection against infectious diseases, including, but not limited to, viral, bacterial, and/or parasitic diseases, such as influenza, AIDS, hepatotisis virus infection, cholera, malaria and tuberculosis, and many other diseases. For example, influenza infections are the seventh leading cause of death in the United States with 200,000 hospitalizations and 40,000 deaths seen in the United States per year and cause about 3-5 million hospitalizations and about 300,000 to 500,000 deaths worldwide per year. Millions of people receive flu vaccines to protect them from seasonal flu each year. Vaccination can also rapidly prevent the spread of an emerging influenze pandemic.
A typical vaccine contains an agent that resembles a weakened or dead form of the disease-causing agent, which could be a microorganism, such as bacteria, virus, fungi, parasites, or one or more toxins and/or one or more proteins, for example, surface proteins, (i.e., antigens) of such a microorganism. The antigen or agent in the vaccine can stimulate the body's immune system to recognize the agent as a foreign invader, generate antibodies against it, destroy it and develop a memory of it. The vaccine-induced memory enables the immune system to act quickly to protect the body from any of these agents that it later encounters.
Vaccine production used in the art e.g., antigen vaccine production, has several stages, including the generation of antigens, antigen purification and inactivation, and vaccine formulation. First, the antigen is generated through culturing viruses in cell lines, growing bacteria in bioreactors, or producing recombinant proteins derived from viruses and bacteria in cell cultures, yeast or bacteria. Recombinant proteins are then purified and the viruses and bacteria are inactivated before they are formulated with adjuvants in vaccines. It has been a challenge to drastically reduce the time and expense associated with current technologies in vaccine development.
Another obstacle to the development of new vaccine is the constant evolution of most infectious agents, such as viruses and bacteria. Viruses often mutate their surface proteins to generate new antigens which can help them skipping the active immune system that has been immunized by vaccines containing the viruses. In contrast, bacteria acquire and mutate key proteins to evade host defense and effective antibiotic applications.
For example, influenza A, B and C viruses are the etiological agents of influenza. Hemagglutinin (HA), the major envelop glycoprotein of influenza A and B viruses, or its homologue, hemagglutinin-esterase (HE) in influenza C virus, is the natural reservoir of the viruses. The rapid evolution of the hemagglutinin (HA) protein of the influenza virus results in the constant emergence of new strains, rendering the adaptive immune response of the host only partially protective to new infections. The biggest challenge for therapy and prophylaxis against influenza and other infections using traditional vaccines is the limitation of vaccines in breadth, providing protection only against closely related subtypes. In addition, today's length of the production process inhibits any fast reaction to develop and produce an adapted vaccine in a pandemic situation.
It is of great interest to develop new vaccines as well as new approaches to combating infectious disease and infectious agents.